NEW DELHI, Oct 11 (Reuters) - India’s oil imports from Iran edged up in September from the previous month as refiners pushed back loading of some August cargoes due to a delay in obtaining government approval to use Iranian ships and insurance, data obtained from sources showed.

Last month, India shipped in about 528,000 barrels per day (bpd) oil from Iran, about 1 percent more than the 523,000 bpd of August and about 27 percent more than a year earlier, tanker arrival data obtained from shipping and industry sources showed.

“Refiners had to delay lifting of some cargoes to late-August and early September as the government permission to use Iranian ships and insurance came in the last week of August ... We could not lift full volumes in August because of this,” said a source at one of the state refiners.

Data from other sources, such as from the Institute of International Finance, show that Iranian oil exports are declining before the United States imposes sanctions on Iran’s oil sector on Nov. 4 after pulling out of an international agreement on Iran’s nuclear activities.

India’s oil imports from Iran plunged by a third in August compared with July, after most insurers and reinsurers backed out of trade with Iran to avoid falling foul of the sanctions given their large exposure to the United States.

About 44 percent of the Iranian oil volumes that arrived in India in September were originally meant for August lifting, the data showed. This was confirmed by officials at the two state-refiners.

India’s September oil imports were also boosted by the import of 2 million barrels of Iranian oil by Reliance Industries Ltd. Reliance did not respond to a Reuters email seeking comments.

Reliance, owner of the world’s biggest refining complex, plans to stop importing Iranian oil in October or November.

Iran continued to be the third biggest oil supplier to India in September, after Iraq and Saudi Arabia.

India, Iran’s top oil client after China, was one of the few nations that continued to trade with the Middle Eastern country when sanctions were previously in force.

New Delhi wants to continue purchasing Iranian oil through this round of sanctions, although it is preparing to trim imports to win waivers from the United States.

Indian refiners have already placed orders to buy 9 million barrels, or about 300,000 bpd, of Iranian oil in November, industry sources told Reuters last week. Oil minister Dharmendra Pradhan confirmed that two Indian refiners will lift Iranian oil in November.

India’s November loading of Iranian oil will be sharply lower than its purchases in the April to September period.

Between April and September, the first half of India’s financial year, the country’s oil imports from Iran surged 40 percent to 627,000 bpd, tanker arrival data showed.

In January-September, India’s oil imports from Iran rose by 21 percent to 592,000 bpd, the data showed. India had reduced purchases from Tehran last year due to a dispute over development rights of a giant gas field.

The South Asian nation was hoping to lift significantly higher volumes in the current fiscal year, after Tehran offered a discount on shipping and an extended credit period, before the U.S. decision on sanctions changed its plans.